The point is that a SCU does not exist, has no physical reality as a whole, so cannot have a beginning as a whole, so we cannot even say that it was, is created or that it created or is creating itself. A SCU therefore doesn't have a cause, nor does it live in a time continuum not of its own making. A SCU is somewhat like a zero continuously splitting itself in positive and negative numbers, their sum always nil, so exists only exists as seen from within, by an observing particle, for example, a particle which is part of the sum which is to stay nil. As there's nothing outside the universe, no warden outside of it to prevent anything to happen inside, things can appear and happen as long this sum stays nil: they have no physical reality to an imaginary outside observer.
Nature's trick to keep the grand total of everything inside the universe nil is to design energy as something the sign of which alternates in space and time, which is why a particle is a wave phenomenon, the magnitude of its energy varying within every cycle even if the period of the cycle, the frequency of the alternation does not. The problem of the present idea that energy is an objectively observable quantity which is always positive is that in such universe conservation laws are violated.
The uncertainty principle is interpreted to say that virtual particle antiparticle-pairs are continuously created out of nothing, to annihilate each other after a time inversely proportional to their energy, energy they supposedly borrow from the vacuum, which, again, is a violation of conservation laws.
In contrast, in a SCU particles only exist to each other if, as far and for as long as they interact, so here they don't borrow energy from the vacuum but from each other: the particle borrows energy from its antiparticle which then pops up with an equal, negative energy, or, what's the same, in counter phase, so here there's no conservation law violated and the total energy of the universe stays nil. The fact that energy is expressed as a frequency, which cannot be a negative number, does not mean that energy itself is a positive quantity, always: if particles only exist to each other if they interact, then their energy sign, the phase they are in with respect to each other is relative, depending on their distance, for example.
The 'magic' is that in a SCU virtual particles become real ones as soon as they manage to set up a continuous energy exchange so they reappear after very disappearance: as they only exist to each other if they interact, exchange energy, no conservation law is violated, so there is no hocus pocus involved in their creation. The energy of a real particle then equals (h = 1) the frequency at which its energy sign alternates, the frequency it pops up, disappears and pops up again etcetera, so in a SCU particles preserve and express their mass by continuously exchanging energy.
As a SCU doesn't exist as a whole, as ' seen' from without, from the imaginary vantage point bigbang cosmologists abide to look at the universe, it obviously doesn't have a beginning, nor has it any cause.
Since in a SCU particles create, cause each other, they explain each other in a circular way, so here we can take any element of an explanation, any link of the chain of reasoning without proof, use it to explain the next link and so on, to follow the circle back to the assumption we started with, which this time is explained by the foregoing reasoning, that is, if our reasoning is sound and our assumptions are valid. If we have more confidence in a theory as it is more consistent and it is more consistent as it relates more phenomena, makes more facts explain each other and needs less additional axioms, less more or less arbitrary assumptions to link one step to the next, then any good theory has a tautological character, fitting a self-creating, self-explaining universe. The circle of reasoning ought to work equally well in the reverse direction.
For a more extensive discussion of the self-creation process, see my website www.quantumgravity.nl, though I have to warn you that a) this is a qualitative study, a work in progress, and b) that I am an awfully bad writer so you may find it hard to read. Another, perhaps more insurmountable obstacle to make sense of the study is that the way we look at things is so conditioned by our belief in causality, that it is very hard to even consider the possibility that nature at its most fundamental (quantum) level simply is non-causal.